The present invention relates to an illuminated display device for displaying an image from a series of image portions on an image sheet. The invention has particular application for, but is not limited to, xe2x80x9cPoint of Salexe2x80x9d or xe2x80x9cCommercial Posterxe2x80x9d advertising.
There are several means of advertising by illuminated display devices or cabinets, catering for a range of poster sizes. Most of such display devices display a single advert. The advert is usually printed on paper which is secured to the front of a diffuser platen and then backlit.
There are known illuminated display devices which illuminate an image sheet, for example, an ink jet print or a photographic print, the image sheet comprising two series of image portions in strip form strategically placed behind, or in front of, a mask sheet, or grid, the mask sheet having a series of transparent windows alternating with a series of opaque strips, either the mask sheet or the image sheet being moved so that the two series of image portions on the image sheet are aligned, in turn, with the series of transparent windows on the mask sheet, thereby permitting an image formed from one of the two series of strip images, to be visible.
It will be appreciated that the clarity of each of the images, the changeover of the images and the dwell time on each of the images is of paramount importance to the advertiser. This is determined by the precision of both the assembly of the image sheet and the matching mask sheet and the drive means and tensioning means used to move the image sheet and the mask sheet relative to one another.
Previous designs, in both respects, have limited the dimensions of illuminated display devices and have been associated with significant drawbacks in terms of clarity of each of the visible images.
The present invention overcomes the limitations associated with known illuminated display devices and achieves an illuminated display device without the previous restrictions as to its dimensions and stability under varying atmospheric conditions. This enables the illuminated display device of the present invention to be used in all recognised sizes thereby vastly increasing its potential customer base.
According to the invention there is provided an illuminated display device comprising an illuminated image sheet, comprising a plurality of series of image portions; a mask sheet having alternate opaque and transparent strips, the mask sheet being located in face-to-face relation to the image sheet; first and second roller means in a substantially parallel spaced-apart arrangement relative to the image sheet and the mask sheet, the first and second roller means being operatively associated with one of the image sheet and the mask sheet; and means to oscillatingly move the one of the image sheet and the mask sheet relative to the other of the image sheet and the mask sheet, the moving means including a drive means; a cam rotatably driven by the drive means; a cam follower lever associated with the cam; and a crank mechanism comprising a crank lever operatively associated with the first roller means and a linkage mechanism connecting the cam follower lever and the crank lever.
Preferably, the image sheet comprises at least three series of image portions, preferably at least four series, most preferably five series.
The illuminated display device of the present invention is suitable for interior and exterior displays. The illuminated display device of the present invention enables a number of images to be viewed in turn. Depending on whether the illuminated display device is for interior or exterior end use, the display device may be illuminated from differing angles, for example, back-illuminated, side-illuminated or front-illuminated by, for example, sunlight or an external light source.
The visible image may comprise several separate images or, alternatively, several images creating a story line or, further alternatively, several images arranged to provide the perception of animated movement.
The display device of the present invention usually has three sections: a substantially rigid rear housing, which may contain a light source (if back-illuminated), for installation, for example, on a display stand or, more usually, on a wall; a front housing having a protective screen cover which optionally has a non-reflecting surface and which can also contain a light source (if front-illuminated); and a centre section comprising an image sheet, a mask sheet or grid having at least one series of transparent windows alternating with a series of opaque strips (opaque in this context means substantially non-transparent), the mask sheet being located in face to face relation to the image sheet; and the means to move the image sheet and the mask sheet in relation to one another. If desired, the centre section can also contain a light source for back-illumination.
Advantageously, two opposing cam follower levers and two opposing crank mechanisms are provided so that the drive means is arranged, in operative association with the first and second roller means, to impart oscillating movement to the first roller means and equal and opposite oscillating movement to the second roller means.
Preferably, the length of the first and second roller means is 10%-50% of the width of the image sheet.
More preferably, the one of the image sheet and the mask sheet which is operatively associated with the first and second roller means is tensioned by providing at least one pair of tension springs, the, or each, pair of tension springs forming a substantially V-shaped arrangement of tension lines, the apex of the substantially V-shaped arrangement being the transverse mid-line of the opposite roller means; and an opposing at least one pair of tension springs forming a substantially inverted V-shaped arrangement of tension lines, the substantially inverted V-shaped arrangement apex being the transverse mid-line of the opposite roller means.
Advantageously, the image sheet and the mask sheet are supported on a platen and the maximum height of curvature of the platen in the y-axis is between 0.3 and 2%, preferably 0.8%, of the length of the platen in the y-axis.
More advantageously, the tension springs are arranged below a notional extension of the y-axis curvature of the platen.
Even more advantageously, the platen has a maximum transverse curvature of between 3% and 20% of the maximum longitudinal curvature of the platen.
Preferably, each image portion forming one series of image portions has a pitch of 0.025-0.25%, preferably 0.05-0.21%, most preferably 0.075-0.15%, of the y-axis length of the image sheet.
More preferably, each transparent window of the mask sheet has a pitch of 30-60%, preferably about 45%, of the pitch of each image portion.
It will be appreciated that, as a consequence of the substantially parallel configuration of the first and second roller means relative to the image sheet and the mask sheet, many advantages ensue.
Specifically, the substantially parallel configuration of first and second roller means permits wide variations in the dimensions of the image sheet and the mask sheet, for example, within the range of A4, A3, A2, A1, A0 to six sheet dimensions. Table 1 shows the x-axis (transverse) and y-axis (longitudinal) dimensions of such sheets, although it will be appreciated that, when used in landscape format, the x-axis and y-axis dimensions are transposed. Equally, the illuminated display device of the present invention can be used to display intermediate sizes or larger sizes, depending on the desired end application. In addition, the illuminated display device of the invention can accommodate additional combination dimensions, for example, A0 wide (840 mm) and A4 high (235 mm).
Provision of third and fourth roller means (not shown) at right angles to the first and second roller means, with a second drive means (not shown) operatively associated with the third roller means and, preferably, with the fourth roller means, permits the display of a series of images in either portrait or landscape configuration, as desired.
It will be appreciated that the one of the mask sheet and the image sheet which is oscillatingly moved under the influence of the moving means, is, in effect, an integral part of the moving means. This integral role results in improved clarity of the displayed image.
Furthermore, the dimensional flexibility of the image sheet and the mask sheet opens the way for further opportunities in the arrangement of images on the image sheetxe2x80x94previously only two or three series of image portions in strip form have usually been used on a single image sheet.
Due to the improved moving means of the present invention, up to five full series of non-animated image portions in strip form can be incorporated on an image sheet for use in an illuminated display device of the invention. Equally, up to ten full series of animated image portions in strip form can be incorporated on an image sheet. In addition, the image sheet can incorporate various series of image portions arranged in a grid configuration, so that several images are on display at the same time. Thus, up to five sequential images can be displayed in a grid configuration, each composed of several individual images.